Good morning: as the political world recovers from the shock of Rick Santorum rocketing up in the latest poll of Iowa Republican voters, the field of GOP presidential candidates is showing increasing desperation with only five days remaining until Iowa's caucuses.

Michele Bachmann's stumbling campaign received a bitter blow late last night when its Iowa co-chair dramatically announced that he was jumping ship to support the surging Ron Paul – setting off a bitter war of words from Bachmann.

As the pace of campaigning reaches fever pitch, the candidates risk slips of the tongue, as both Rick Perry and Mitt Romney discovered – Perry appearing to count Canada as part of the US and Romney threatening popular children's television show Sesame Street.

In other words, another typical day on the campaign trail in Iowa – and we'll be following all the action here live.

It's not Mitt Romney or Newt Gingrich or Ron Paul. It's Obama for America, the president's re-election campaign, which badly wants to win this battleground state in November, as it did in 2008.

9.31am: So where in Iowa are the candidates today?

• Mitt Romney: Started early with a breakfast meeting. Various events planned, the highlight being a meet and greet at Music Man Square in Mason City – Mason City being the original model for "River City, Iowa" in the musical The Music Man.

Expect Romney to give a speech along the lines of "We've got trouble, right here in Mason City," and propose a boy's marching band with 76 trombones as the solution.

• Newt Gingrich: A hectic round of events and town halls, capped off with a visit at 7pm CT to the Santa Maria Vineyard and Winery in Carroll, Iowa. Yes, Newt Gingrich is visiting a vineyard in Iowa.

• Rick Perry: Continues his bus tour of Iowa, including a 12.30pm stop at the Blue Strawberry Coffee Company in Cedar Rapids.

• Ron Paul: Three town hall meetings across the state, but kicking off the day with an in-studio interview with Jan Mickelson on WHO Radio. Ron Paul, that's WHO.

• Michele Bachmann: No visits to a single Pizza Ranch outlet today, although she fits a meet and greet in at the Snack Time Family Restaurant in Nevada. That's Nevada, Iowa – something that will really confuse Rick Perry.

• Rick Santorum: More town halls, finishing up with a rally at the Center for Active Seniors in Davenport. Active enough to get to the caucuses, Santorum hopes.

• Jon Huntsman: Stealth campaign to win Iowa continues with meeting at the Page Belting Company in Laconia, New Hampshire.

10am: Another sign Ron Paul is being taken very seriously: a Jewish human rights organisation wants him to explain some of his alleged views on Israel.

Rabbi Marvin Hier and Rabbi Abraham Cooper of the Simon Wiesenthal Centre say in a statement released this morning:

While the Presidential campaign is not focused on Israel, these are serious charges. We must be fair to Ron Paul and give him the opportunity to clarify his position and he must be honest with the American people before they are asked to cast their vote for the most powerful office in the world.

10.15am: The always excellent Larry Sabato of the University of Virginia looks into his Crystal Ball and sees four possible scenarios coming out of the Iowa caucuses. Such as this one:

Scenario 3: Inconclusive result clouds the future

What if Romney, Gingrich and Paul ended up with nearly the same percentage of the caucus vote, keeping anyone from claiming a credible mandate or generating momentum?

Gingrich has exploited conservatism, because he has profited not by advancing the cause, but by harming it. He made money as a consultant and lobbyist trying to convince conservatives to support subsidies for housing, prescription drugs and ethanol. And this year, he has profited by temporarily convincing millions of conservatives that he's the right man to beat Obama.

There's a popular saying about causes that "start as a mass movement, become a business, and end up a racket." With Gingrich, a movement that changed American politics in 1994 has evolved into a Tiffany-studded, jet-setting lifestyle.

Actually, if Romney was half this exciting the GOP race would be all over by now.

11.15am: The Guardian's Ewen MacAskill is on the ground in Iowa and reports on the possible collapse of Michele Bachmann's campaign after the shock defection of one of her biggest Iowa supporters last night:

Five days left to the Iowa caucus and the Bachmann campaign looks as if it is imploding. Bad enough that the state chairman of her campaign, Kent Sorenson, defects to the Ron Paul campaign. But this morning her Iowa political director, Wes Enos, disavows her claim that Sorenson left for financial reasons.

Enos, in a statement, said there is no way money is involved: "I cannot, in good conscious watch a good man like Ken Sorenson be attacked as a 'sell-out'." What chance Enos is still part of her campaign by midnight tonight?

Bachmann has had problems holding staff before. The veteran political strategist, Ed Rollins, quit earlier this year. He initially cited health reasons but later criticised her for refusing to listen and for being short of campaign funds. But this is much, much worse. If she comes in fourth in Iowa, will she carry on to New Hampshire and South Carolina or, more likely, just drop out?

After the state senator from Indianola stunned Iowa political watchers by showing up on stage at a Paul rally late Wednesday, the Bachmann campaign released a statement from the candidate accusing Sorenson of leaving for money.

"Kent Sorenson personally told me he was offered a large sum of money to go to work for the Paul campaign," Bachmann said.

At this point Bachmann will be lucky to come fourth, which would mean she would finish ahead of one of Ron Paul, Romney, Gingrich or Santorum. Fifth or sixth place is more likely – and that will finish off her campaign.

11.31am: How confident is Mitt Romney of winning in Iowa? Pretty confident, after the news that Romney is staying in Iowa on Tuesday night, rather than fleeing to New Hampshire.

On Tuesday night, the Romney campaign will host a post-caucus party at the Hotel Fort Des Moines. The candidate will give remarks, and he and his wife and some of his five sons will mingle with supporters, Romney's Iowa consultant David Kochel said.

The next morning, the former governor will do press interviews before flying to New Hampshire, the next state on the voting calendar and a crucial contest for Romney.

Standard operating procedure is to leave town as soon as possible if you are not going to bask in the winner's circle limelight. So by staying the extra day, that suggests Romney is confident of doing well in both Iowa and New Hampshire.

The latest national telephone survey finds that 45% of Likely US Voters favor the former Massachusetts governor, while 39% prefer the president.

12.15pm: More bad news for Michele Bachmann? This nugget comes from the Associated Press in Des Moines:

Two politically active pastors in Iowa's robust evangelical conservative movement disclosed an effort to persuade either Santorum or Bachmann to quit the race and endorse the other. "Otherwise, like-minded people will be divided and water down their impact," said Rev. Cary Gordon, a Sioux City minister and a leader among Iowa's social conservatives.

It looks as if Santorum has become the default evangelical conservative candidate, based on the latest polling. Maybe Bachmann should have taken the chance to get out while the going was good-ish.

12.30pm: A really good attack ad metaphorically puts its boot on your opponent's throat and kicks him in the head with the other boot.

Which is basically what this new Restore Our Future – Mitt Romney-backing Super Pac – ad does to Newt Gingrich on Iowa's TV screens.

12.41pm: More polls, although smaller and less robust than Rasmussen's poll reported earlier.

Forty-one percent (41%) of all caucus participants say they still could change their minds, and 6% more have no first preference, suggesting that much could still change in the next five days.

Among voters who could still change their minds, Romney remains the leading second choice with 20% support. Perry and Santorum are next with 17% support each, followed by Gingrich and Paul who both earn 12% of the vote.

That suggests to me a Romney win, because of his higher ceiling, compared with Paul. And a hint that Santorum or Perry may do better than expected.

1.05pm: How far has Newt Gingrich fallen? According to the RealClearPolitics rolling average, 18 days ago Gingrich was polling in first place with 31% in Iowa. Today, counting the two new polls that have been published, Gingrich gets 14% and a tie for third with Santorum.

"I was always in the Ron Paul camp before Michele Bachmann came onto the scene," says Sorenson, describing his election as a state senator in a tough political environment. "The only people who came to my aid in 2008 was the Ron Paul people."

2.13pm: The Occupy the Caucuses movment is in action again, with five members being arrested outside of Ron Paul's Iowa campaign headquarters.

Ron Paul doesn't seem an obvious target, given his hostility to Wall Street and big banks. But today's protest was over Paul's proposal to shot down the Environmental Protection Agency.

A spokesperson for Occupy the Caucuses said the plan is for protesters to go to the campaign headquarters of each Republican candidate and President Barack Obama's campaign office before the weekend.

2.21pm: The Associated Press has another wrinkle in the Kent Sorenson affair:

Susan Geddes, a veteran operative in conservative GOP political circles who managed Sorenson's 2008 and 2010 legislative races, said Sorenson had told her several times, as recently as last month, that the Paul campaign had offered him money to leave Bachmann's campaign for the Texas congressman's.

Geddes said Sorenson had damaged his political future in Iowa by abandoning Bachmann's campaign less than a week before the caucuses.

"He just committed political suicide," she said.

2.30pm: At last, Rick Santorum has done well enough to merit his own attack ad – from Rick Perry, in the battle for the bronze medal.

A strong finish in Iowa, the first of the contests to choose a Republican nominee to take on Barack Obama, would provide Romney with momentum for those that follow and could wrap up the race for the nomination by the end of the month.

3pm: This is how political campaigns die: not with a bang but a whimper. Via the Associated Press:

On Thursday, Bachmann dismissed the idea that her campaign was in disarray following the departure of former Iowa chairman Kent Sorenson the night before. She said her campaign organization is strong and that she is looking ahead to Tuesday's first-in-the-nation caucuses.

3.10pm: Trying to find a better source for this, but there's another poll out from Iowa, this time from ARG, not famously accurate but there we are.

Paul doesn't need a sidekick to fill his plate at the breakfast buffet, fetch his coffee, whisper talking points into his ear, or get rid of pesky reporters – he does that all himself, thank you very much. Asked if he's concerned that if he doesn't win his followers will not rally behind the GOP nominee, he looks up from his plate of cantaloupe, honeydew, eggs, sausage and biscuit and says brusquely, "Right now, the only thing that bothers me is people who don't respect my privacy enough to leave me alone for five minutes when I'm eating breakfast." And then he goes back to reading his USA Today.

Charming. (By the way, if this were to happen to Romney, which it wouldn't, a SWAT team would immediately surround the reporter to oversee damage control.)

3.52pm: One of the reasons the Iowa race is exciting is because it's close. New Hampshire, the so-called "First In The Nation" primary, is dull as ditchwater because of next-door neighbour Mitt Romney's domination there. Pollsters PPP report from their latest poll:

Mitt Romney continues to have a solid lead in the state with 36% to 21% for Paul, 13% for Gingrich, 12% for Jon Huntsman, 7% for Michele Bachmann, and 3% each for Buddy Roemer, Rick Perry, and Rick Santorum. Every candidate is within two points of their standing when PPP polled New Hampshire two weekends ago with the exception of Gingrich, who has dropped from 17% to 13%.

There's little to suggest anyone could come from behind to defeat Romney in New Hampshire. He has the best favorability numbers in the state at 63/32 and 78% of his supporters are strongly committed to him, higher even than Paul's number on that front.

Gingrich finishing a bad third or fouth would nearly knock him out. And a third might be the best Huntsman can do.

Mitt Romney has edged ahead of Newt Gingrich, 27% to 23%, for the national lead among Republican voters for the first time since Gallup Daily tracking of the Republican race began on December 1. Ron Paul remains in deep third place with 11% of the GOP vote, followed by Rick Perry at 8%.

4.30pm: Michele Bachmann is trying to channel Margaret Thatcher on the stump in Iowa.

For the third time today, Bachmann says she wants to be "America's iron lady," a la Margaret Thatcher. #iacaucus

That tweet is from the Politico's Juana Summers.

Obviously Bachmann hasn't looked too closely at Thatcher's record. Maggie is way too liberal to win the Iowa caucuses, let along the Republican nomination. You think Obamacare is bad? Thatcher once said the NHS was "safe in my hands". Basically she was a socialist in Amnerican political terms.

4.45pm: Campaign television ad spending in Iowa reaches more than $12m, the AP's Beth Fouhy reports, much of it in the closing days of the campaign:

At least $12.5 million and counting has blanketed the airwaves ahead of next Tuesday's Republican presidential caucuses, with hard-hitting commercials awash in ghoulish images and startling claims. Most are coming from a proliferation of new independent groups aligned with the candidates.

I was never offered money from the Ron Paul campaign or anyone associated with them.

The latest development is that Wes Enos – Bachmann's political director who defended Sorenson against Bachmann's allegations that Sorenson was offered money to change sides – is said to "no longer be with the campaign".

Meanwhile, here's a video from Yahoo's David Chalian talking to Ron Paul supporters and potential supporters in Iowa.

5.50pm: Several people have been arrested outside the Democratic party headquarters in Des Moines during a protest by the Occupy the Caucus and Occupy Des Moines groups.